Welcome aboard! The last thing any of us here are worried about is anyone knowing the "lingo". Your just as welcome here as anyone else that needs help with there atv!
Saying they even make them for that quad. Sport quads have them for when we go long travel for racing. With gncc racing branching out into utility quad racing there is a chance atleast.
Unfortunately I don’t have any pictures on my phone right now but I’ll post some when I get home. Sounds like if I want to fix it I need to get some aftermarket A arms
Welcome aboard! Got any pictures? The 400ex's im used to working on are well known for being welded in the factory with jigs that werent set up right. Alot of them are noticably cambered from the factory on only one side. Almost all the aftermarket a-arm manufacturers have gone to replaceable upper and lower ball joints that are threaded so they can be adjusted compensate for this.